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Beneficial rainfall for some

August 17, 2012

Beneficial rainfall for some

The first half of August brought some significant rainfall to many
areas of the state, and in somewhat heavy doses in places.
Thunderstorms brought 1.56 inches to International Falls and 1.40 inches
to Red Wing Dam on August 15th. Some areas south of the Twin Cities
(New Prague, Farmington, Rosemount) also received over 1 inch from fast
moving thunderstorms on the 15th. In addition some hail over 1 inch in
diameter fell over western counties on the 15th.

Many observers
have reported over 2 inches for the month so far, while some locations
(Preston, Lanesboro, Caledonia, Grand Portage) have received over 3
inches, as much as 3.59 inches at Grand Portage and 3.57 inches at
Caldonia. The rainfall so far this month has kept the Minnesota drought
stricken area from expanding in size this month.

Temperatures
are averaging from 1 to 3 degrees F cooler than normal so far this
month. For six consecutive days over August 9-14 daily temperatures
were cooler than normal, a stretch of cooler than normal weather not
seen since June 22-28, 2011 (15 months ago). Many observers have
already reported overnight lows in the 30s F this month. Meanwhile at
the Amundsen-Scott Station at the South Pole (Antarctica) it was -77
degrees F this week.

Despite cooler than normal temperatures,
crops are rapidly maturing well ahead of the normal calendar pace. Corn
will be ready for early harvest, while sugar beets are already being
lifted in some places.

Record cold in places

August 16th brought a record-tying low temperature to International
Falls with a reading of 41 degrees F (tied 1958). But more
significantly a strong Canadian high pressure ridge brought the coldest
August 17th (Fri) since 1963 to many parts of the state. New record low
temperatures were set at: Silver Bay (34 F); Hibbing (34 F); Crane Lake
(36 F); Princeton (37 F); Austin (38 F); and Waseca (39 F). In
addition many observers reported tying their record cold low
temperatures on August 17th including, 36 degrees F at Fosston (tied
2007), 37 degrees F at Little Falls (tied 1999); 37 degrees F at Hallock
(tied 1904); and 39 degrees F at Park Rapids (tied 1896). For many
these were the coldest readings since May 16th last spring.

New Seasonal Climate Outlooks

The NOAA Climate Prediction Center issued new seasonal climate
outlooks on Thursday (August 16th) covering the period from September to
November. September is expected to be warmer than normal for much of
the nation's midsection, following a trend of recent years. Over
September to November Minnesota is expected to see above normal
temperatures prevail, a pattern associated with a developing El Nino
episode. The CPC sees equal chances for above or below normal
precipitation across Minnesota during this period.

NOAA also
released a new Drought Outlook this week, covering the period through
November 30th. The outlook calls for drought improvement in Minnesota,
northeastern Iowa, southern Wisconsin, and northern Illinois.
Unfortunately the outlook favors drought persistence in southwestern
Iowa, Nebraska, Missouri, and southern Illinois.

Weekly Weather potpourri

Typhoon Kai-Tak located southeast of Hong Kong was being monitored
carefully this week. It packed winds up to 90 mph, producing sea waves
of 25 feet. Kai-Tak is expected to bring heavy rains to areas between
Hong Kong and Hanoi this weekend.

Tropical Storm Gordon formed in
the North Atlantic on August 16th east of Bermuda. It is expected to
strengthen slightly and perhaps become a hurricane over the weekend as
it head toward the Azores. Gordon is the 7th named storm of the North
Atlantic Tropical Storm season. The National Hurricane Center was also
monitoring a depression in the southern Gulf of Mexico which may become a
tropical storm over the weekend.

A recent study published in the
journal Geology documents a 7000 year history of climate in the Nile
Delta of Egypt. Based on interpretations of pollen and charcoal records
from river sediments researchers have found evidence for mega-droughts
in the region at 5000 years ago, 4200 years ago, and 3000 years ago.
The mega-drought 4200 years ago was associated with the collapse Egypt's
Old Kingdom. You can read more about this study here.

On Thursday (Aug 16) parts of Siberia reported strong thunderstorms with
heavy rain and large hail, some the size of hen's eggs. Hundreds of
cars were damaged by the hailstones. Following the passage of the
thunderstorm the temperature dropped from 90 degrees F to just 61
degrees F.

MPR listener question

Here in the Twin Cities we recorded daytime highs of 92 F and 90 F
on August 1st and 2nd, but since then we have not seen 90 degrees F.
How often does August produce no 90 F days in the Twin Cities climate
record, and do you think we'll see another 90 F this month?

Answer:
According to the Twin Cities climate record about 1 year in 9 August
brings no days with temperatures of 90s degrees F or greater. In fact
just last year was such an August. Given the present forecast for the
balance of the month I see a very low probability for another 90 F day
in the Twin Cities. However, bear in mind that about 40 percent of the
time September brings at least one 90 F day to the Twin Cities.

Twin Cities Almanac for August 17th

The average MSP high temperature for this date is 82 degrees F (plus or
minus 8 degrees F standard deviation), while the average low is 61
degrees F (plus or minus 6 degrees F standard deviation).

Average dew point for August 17th is 59 degrees F, with a maximum of 80 degrees F in 2002 and a minimum of 42 degrees F in 1947.

All-time state records for August 17th

The state record high temperature for this date is 105 degrees F at
Campbell (Wilkin County) in 1988. The state record low temperature for
this date is 29 degrees F at Tower (St Louis County) in 1981. State
record precipitation for this date is 5.00 inches at Le Center (Le Sueur
County) in 1948; and no snowfall has been reported on this date.

Past Weather Features:

August
17, 1963 brought cold temperatures to parts of northern Minnesota.
Frost was reported at Cook, Virginia and Bigfork. Temperatures
rebounded to the mid-80s F by the 20th.

Another cold August 17 in
1981 when several northern communities reported frost. Cotton, Hoyt
Lakes, Virginia, Meadowlands, Hibbing, and Tower reported frost on that
date.

The hottest August 17th in history was probably 1988 when
over 20 Minnesota communities reported afternoon temperatures of 100
degrees F or greater. Actually the August heat wave lasted from the
15th to the 17th, finally breaking with the passage of a cold front on
the 18th which dropped daytime highs by 25 degrees F.

Outlook

Cooler than normal weekend under mostly sunny skies. Warming trend
begins on Tuesday and will push temperatures back close to normal with
another chance for showers and thunderstorms by Wednesday and Thursday.